Thanks for the advice on using cairo.Matrix! I just spent a lot of time cleaning up the code, consolidating and organizing, and making sure I'm calling the right functions. I've now fixed up that bug and got the scrollbars working! Thanks a lot.
On Sat, Sep 10, 2011 at 6:21 AM, Pietro Battiston <m...@pietrobattiston.it> wrote: > Il giorno ven, 09/09/2011 alle 12.42 -0400, Jamie Bliss ha scritto: >> This might be considered off-topic, but this is the closest I could >> think of. I need help trying to track down a bug. >> >> I have an application I'm working called cropper. (Screenshot: >> <http://imgur.com/iIUCu> Source: >> <https://github.com/astronouth7303/cropper>) It's basically a tool >> that lets you crop an image in multiple ways at once. >> >> It's currently suffering from a number of major bugs, but the big one >> that's really bothering me atm is zooming. >> >> The "workspace" is a single custom widget (ImageSpace, in >> imagespace.py) wrapped in a ScrolledWindow. It has the ability to zoom >> in and out on the content (by setting the zoom property, 1.0 is >> normal, 2.0 is twice as big, 0.5 is half as big). The problem is that >> when zoom != 1.0, it doesn't transform coordinates between the image >> space and widget space correctly. >> >> For calculations and such, I define two methods (img2widgetcoords and >> widget2imgcoords) for this transformation. (The image is always >> centered in the widget.) But for drawing, I'm using cairo's >> transformation methods. >> >> As far as I can tell, these two methods should produce the same >> results. But somehow, something's wrong. It's exhibited when creating >> new boxes, in the calculation cache system, and looking at output I >> made specifically for debug (the spot that widget2imgcoords calls >> (0,0) isn't where the upper-right corner of the image). >> >> Does anyone have any experience they can offer on this? Is this just a >> disconnect between cairo's methods and mine? Am I just doing something >> wrong? >> > > Hello Jamie, > > I just gave a very brief look at your code, and have a very brief > suggestion: have you considered using directly Cairo matrix objects to > manage coordinates changes? > > That's what I did - notice my problem was sligthly different from yours, > and that code is probably in non-working state - for instance here: > > git clone git://pietrobattiston.it/spilla > > (if I remember correctly, for instance "transform_point" used in > spillamod/operations.py) and it was very useful - I can always make > drawing bugs, but once I draw, I know clicks are in sync with the > drawing. > >> Thank you, > > You're welcome, good luck! > > Pietro > > _______________________________________________ > pygtk mailing list pygtk@daa.com.au > http://www.daa.com.au/mailman/listinfo/pygtk > Read the PyGTK FAQ: http://faq.pygtk.org/ > _______________________________________________ pygtk mailing list pygtk@daa.com.au http://www.daa.com.au/mailman/listinfo/pygtk Read the PyGTK FAQ: http://faq.pygtk.org/
